A HackaTUM 2025 project by Evan Christopher, Chan-Young Lee, Moritz Pötzsch, and Zexin Gong.

SixthGear transforms car rental checkout from a time-consuming queue experience into an instant, personalized conversation with a realistic AI avatar. By combining the efficiency and scalability of digital checkout with the empathy and sales expertise of a human-like agent, we enable car rental companies to deliver superior customer service while maximizing upsell opportunities.

The AI agent guides customers through a complete rental booking process:

1. Greets the customer and validates their booking number
2. Collects trip details through natural conversation (group size, luggage, pets, purpose)
3. Validates driver's license information
4. Fetches available vehicles and protection packages via backend API
5. Recommends personalized upgrades based on customer context and trip details
6. Explains each suggestion with clear reasoning, just like a human sales agent
7. Completes the booking once selections are confirmed

The agent follows a state machine workflow through distinct stages: intro → booking → license → upsell → complete.

Frontend:

• React with Vite
• LiveKit for real-time audio/visual streaming

Backend:

• FastAPI with Python
• OpenAI GPT for conversational intelligence and state management
• OpenAI Speech-to-Text and Text-to-Speech
• LiveKit server integration
• Beyond Presence hyper-realistic AI avatars

External Services:

• Sixt booking APIs
• Beyond Presence avatar rendering
• LiveKit cloud infrastructure

• Node.js (v16 or higher)
• Python (v3.8 or higher)
• A Beyond Presence account
• A LiveKit account
• API keys for OpenAI, Beyond Presence, and LiveKit

Navigate to the backend directory:

cd ./backend

Create and activate a virtual environment:

python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate

Install dependencies:

pip install -r requirements.txt

Create a .env file in the backend folder with the following variables:

LIVEKIT_URL=your_livekit_url
LIVEKIT_API_KEY=your_livekit_api_key
LIVEKIT_API_SECRET=your_livekit_api_secret
BEY_API_KEY=your_beyond_presence_api_key
OPENAI_API_KEY=your_openai_api_key
BEY_AVATAR_ID=your_avatar_id
BOOKING_API_URL=https://hackatum25.sixt.io

Start both backend services in separate terminals:

Terminal 1:

python main.py

Terminal 2:

cd ./src
uvicorn main:app --reload

Navigate to the frontend directory:

cd ./my-app

Install dependencies:

npm install

Start the development server:

npm run dev

The application will be accessible at http://localhost:5173

Intelligent Upselling

Protection packages are recommended according to business logic, with progressive value tiers:

• No Protection → Cover The Car → Peace of Mind → Cover The Car & Liability

Context-Aware Recommendations

The agent analyzes customer context to suggest relevant upgrades. For example:

• Family with pets → Packages with interior protection and liability coverage
• Skiing trip → Enhanced protection for mountain driving
• Business travel → Premium vehicle options with professional amenities

Natural Conversation Flow

Using GPT-based state management, the agent maintains coherent, empathetic dialogue while progressing through the booking workflow. The Beyond Presence avatar provides visual engagement that builds trust and rapport.

Challenges

• Integrating LiveKit with our custom React frontend
• Maintaining natural conversation flow within strict agent state transitions
• Handling LLM nondeterminism while ensuring consistent reasoning
• Balancing response quality with speed for real-time interaction

Key Learnings

• Thorough API documentation review is essential before integration
• Familiar tech stacks are safer choices for hackathon time constraints
• State management requires careful design when working with probabilistic AI models

Video Intelligence

Implement computer vision to analyze customer appearance and vehicle surroundings, enabling more personalized recommendations based on visual context.

Environmental Robustness

Add noise cancellation and audio processing to ensure reliable performance in busy environments like airport rental counters.

Multi-language Support

Expand avatar capabilities to serve customers in their preferred language with natural accent and cultural awareness.

Analytics Dashboard

Build comprehensive analytics to track conversion rates, popular upgrades, and customer satisfaction metrics.

Traditional car rental checkout involves frustrating queues and missed upsell opportunities. While mobile apps reduce wait times, they lack the human touch that drives conversion and customer satisfaction. Real sales agents excel at empathy, timing, and personalized recommendations—qualities that static digital flows cannot replicate.

SixthGear bridges this gap by combining the convenience of instant mobile checkout with the warmth, trust, and conversational intelligence of an experienced human agent.